The present invention relates to a method of manufacturing a semiconductor device comprising the steps of forming a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer and to a film-forming apparatus.
In forming a solar battery panel, which is a semiconductor device, a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor are successively formed one upon the other on the surface of, for example, a glass substrate. These p-type semiconductor layer, i-type semiconductor layer and n-type semiconductor layer are formed to differ from each other in thickness. In general, the p-type semiconductor layer is formed thin to increase the amount of the effective light. Also, the i-type semiconductor layer is formed thick to improve the conversion efficiency. For example, the p-type semiconductor layer is formed in a thickness of about 70 xc3x85, the i-type semiconductor layer is formed in a thickness of about 3000 xc3x85, and the n-type semiconductor layer is formed in a thickness of about 150 xc3x85 in many cases.
Each of the p-type semiconductor layer, the i-type semiconductor layer and the n-type semiconductor layer is formed by a CVD method. The film formation by the CVD method is carried out within a film-forming chamber. In this case, it is known to the art that a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer are successively formed in a single film-forming chamber. In this method, however, the process time is rendered long, leading to a low productivity.
To overcome this difficulty, exclusive film-forming chambers are used for forming successively the p-type semiconductor layer, the i-type semiconductor layer, and the n-type semiconductor layer. It should be noted in this connection that the time required for forming the i-type semiconductor layer, which has the largest thickness, is considerably longer than the time required for forming any of the p-type and n-type semiconductor layers. It is unavoidable for the film-forming chambers for forming the p-type and n-type semiconductor layers to incur a loss time, leading to a low productivity.
On the other hand, the p-type, i-type and n-type semiconductor layers are formed in general at different temperatures. For example, the p-type semiconductor layer acting as a window layer on the side of the incident light is formed at a temperature lower than that for forming the i-type semiconductor layer in order to widen the band gap and to suppress the damage done to the electrode arranged below the p-type semiconductor layer. Also, the i-type semiconductor layer is formed at a temperature higher than that for forming the p-type semiconductor layer in view of the photostability.
Where the p-type, i-type and n-type semiconductor layers are formed in exclusive film-forming chambers arranged in series, each film-forming chamber is set at a temperature adapted for forming the desired semiconductor layer. For example, the film-forming chamber for forming the p-type semiconductor layer is set at about 160xc2x0 C. Also, each of the chambers for forming the i-type and n-type semiconductor layers is set at about 200xc2x0 C.
For improving the productivity in forming semiconductor layers on a substrate in this fashion, it is required to perform temperature control to permit the temperature of the substrate transferred into each of the film-forming chambers to be set at a film-forming temperature within the chamber in a short time. For example, if a p-type semiconductor layer has been formed on a substrate whose temperature has been controlled at 160xc2x0 C., it is necessary to elevate the substrate temperature to about 200xc2x0 C. for forming an i-type semiconductor layer on the p-type semiconductor layer in the next step.
However, even if the substrate is transferred. into the film-forming chamber controlled at a predetermined temperature, it takes time for the substrate to be heated from 160xc2x0 C. to a desired time of 200xc2x0 C., with the result that the process time for forming a semiconductor layer on the substrate is rendered long. By contraries, even if the substrate temperature is set within a short process time, it is difficult to set the substrate temperature at a predetermined temperature within the short time. In addition, if the film-forming chambers are set at different temperatures conforming with the temperatures of the semiconductor layers formed within these chambers, the thermal stress received by the substrate transferred into the film-forming chamber of different temperature is increased. It follows that it is possible for bad effects to be given to the substrate and to the semiconductor layer formed on the substrate.
An object of the present invention is to provide a method of manufacturing a semiconductor device, which permits successively forming a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer on a substrate surface in exclusive film-forming chambers while avoiding a loss time in operation of each of the film-forming chambers.
Another object is to provide an apparatus for manufacturing a semiconductor device, which permits successively forming a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer on a substrate surface in exclusive film-forming chambers while avoiding a loss time in operation of each of the film-forming chambers.
Another object is to provide a method of manufacturing a semiconductor device, which permits successively forming a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer on a substrate surface in a short time in exclusive film-forming chambers while suppressing a thermal stress given to the substrate and to the semiconductor layers formed on the substrate surface.
Still another object of the present invention is to provide an apparatus for manufacturing a semiconductor device, which permits successively forming a p-type semiconductor layer, an i-type semiconductor layer and an n-type semiconductor layer on a substrate surface in a short time in exclusive film-forming chambers while suppressing a thermal stress given to the substrate and to the semiconductor layers formed on the substrate surface.
According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor device, in which a substrate is successively transferred into a first film-forming chamber forming a semiconductor layer of a first conductivity type, a plurality of second film-forming chambers for forming an i-type semiconductor layer and a third film-forming chamber for forming a semiconductor layer of a second conductivity type, the first, second and third film-forming chambers being arranged in series, for successively forming a semiconductor layer of the first conductivity type, an i-type semiconductor layer and a semiconductor layer of the second conductivity type within these first, second and third film-forming chambers, respectively, on the surface of the substrate, the method comprising the step of simultaneously transferring the substrates arranged within the first, second and third film-forming chambers and each having a semiconductor layer formed thereon into adjacent chambers on the downstream side.
According to a second aspect of the present invention, there is provided an apparatus for manufacturing a semiconductor device, comprising a film-forming chamber body including a first film-forming chamber for forming a semiconductor layer of a first conductivity type, a second film-forming chamber for forming an i-type semiconductor layer, and a third film-forming chamber for forming a semiconductor layer of a second conductivity type, which are arranged in series; openable means for opening-closing communication holes formed in partition walls, each partition wall being for partitioning two adjacent film-forming chambers; control means for simultaneously driving all of the openable means so as to control opening-closing of the communication hole made in each of the partition walls; and transfer means for simultaneously transferring in the downstream direction the substrates having a semiconductor layer of the first conductivity type, an i-type semiconductor layer and a semiconductor layer of the second conductivity type formed thereon in the first, second and third film-forming chambers, respectively.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.